System and method for mobile location by dynamic clustering

ABSTRACT

A system and method for determining the location of a mobile device in a communications network. A set of network measurement reports (NMR) may be provided for a region in the network. NMRs in the first set may be clustered as a function of observed measurement information in the NMRs. A candidate NMR for a mobile device may be received, and the candidate NMR may then be associated with a selected cluster of NMRs. The candidate NMR and a second set of NMRs may then be clustered, and a location of the mobile device determined as a function of the clustered candidate NMR and second set of NMRs, where the NMRs in the second set are associated with the selected cluster.

CROSS REFERENCES

The present application is a continuation of U.S. application Ser. No.14/013,329 entitled “System and Method for Mobile Location by DynamicClustering”, filed on 29 Aug. 2013, which is a continuation of U.S.application Ser. No. 13/396,172 entitled “System and Method for MobileLocation by Dynamic Clustering”, filed on 14 Feb. 2012 and issued asU.S. Pat. No. 8,526,968 on 3 Sep. 2013, which itself claims the prioritybenefit of U.S. Provisional Application Ser. No. 61/442,363 entitled“Mobile Location by Dynamic Clustering”, filed on 14 Feb. 2011, theentirety of each of which are incorporated herein by reference.

BACKGROUND

The present disclosure is generally directed towards a system and methodfor estimating the location of a wireless mobile device that is incommunication with a wireless communications network. More specifically,the disclosure relates to the problem of estimating the location of awireless mobile device using information from one or more NetworkMeasurement Reports (“NMRs”) which may be generated by a wirelesscommunications network or the mobile device.

As is well known in the art, the use of wireless communication devicessuch as telephones, pagers, personal digital assistants, laptopcomputers, anti-theft devices, etc., hereinafter referred tocollectively as “mobile devices”, has become prevalent in today'ssociety. Along with the proliferation of these mobile devices is thesafety concern associated with the need to locate the mobile device, forexample in an emergency situation. For example, the FederalCommunication Commission (“FCC”) has issued a geolocation mandate forproviders of wireless telephone communication services that puts inplace a schedule and an accuracy standard under which the providers ofwireless communications must implement geolocation technology forwireless telephones when used to make a 911 emergency telephone call(FCC 94-102 E911). In addition to E911 emergency related issues, therehas been increased interest in technology which can determine thegeographic position, or “geolocate” a mobile device. For example,wireless telecommunications providers are developing location-enabledservices for their subscribers including roadside assistance,turn-by-turn driving directions, concierge services, location-specificbilling rates and location-specific advertising.

Currently in the art, there are a number of different ways to geolocatea mobile device. For example, providers of wireless communicationservices have installed mobile device location capabilities into theirnetworks. In operation, these network overlay location systems takemeasurements on radio frequency (“RF”) transmissions from mobile devicesat base station locations surrounding the mobile device and estimate thelocation of the mobile device with respect to the base stations. Becausethe geographic location of the base stations is known, the determinationof the location of the mobile device with respect to the base stationpermits the geographic location of the mobile device to be determined.The RF measurements of the transmitted signal at the base stations caninclude the time of arrival, the angle of arrival, the signal power, orthe unique/repeatable radio propagation path (radio fingerprinting)derivable features. In addition, the geolocation systems can also usecollateral information, e.g., information other than that derived forthe RF measurement to assist in the geolocation of the mobile device,i.e., location of roads, dead-reckoning, topography, map matching, etc.

In a network-based geolocation system, the mobile device to be locatedis typically identified and radio channel assignments determined by (a)monitoring the control information transmitted on radio channel fortelephone calls being placed by the mobile device or on a wirelineinterface to detect calls of interest, i.e., 911, (b) a location requestprovided by a non-mobile device source, i.e., an enhanced servicesprovider. Once a mobile device to be located has been identified andradio channel assignments determined, the location determining system isfirst tasked to determine the geolocation of the mobile device and thendirected to report the determined position to the requesting entity orenhanced services provider.

The monitoring of the RF transmissions from the mobile device orwireline interfaces to identify calls of interest is known as “tipping”,and generally involves recognizing a call of interest being made from amobile device and collecting the call setup information. Once the mobiledevice is identified and the call setup information is collected, thelocation determining system can be tasked to geolocate the mobiledevice.

While the above-described systems are useful in certain situations,there is a need to streamline the process in order to efficiently andeffectively handle the vast amount of data being sent between thewireless communications network and the large number of mobile devicesfor which locations are to be determined. In this regard, embodiments ofthe present subject matter may overcome the limitations of the prior artby estimating the location of a wireless mobile device using NetworkMeasurement Reports (“NMRs”) which include calibration data for a numberof locations within a geographic region. An NMR may be, in oneembodiment, a vector of measurement observations. Embodiments of thepresent subject matter may provide an accurate location of a mobiledevice using a variety of observations, measured at the mobile or by thenetwork in relation to the mobile. Exemplary pattern matching schemesmay employ these observations and/or associate such observations with adatabase containing previously made observations to determine a locationof a mobile device. Exemplary pattern matching schemes may be providedwith one or more NMRs or a set of such measurements associated with amobile device at its unknown location, a calibration database containingpreviously obtained measurements or predicted measurements indexed tolocation.

One conventional method of location estimation utilizing NMRs is tocompare an NMR from a target mobile device with calibration vectors in arespective measurement database, determine the closest NMR (using somemetric), and assign the location of the closest NMR as the location ofthe NMR for the target mobile device. Such a method, however, providesunacceptable errors, especially when the NMRs contain power measurementsas there may be a large variability in these measurements to reliablylocate the target mobile device. Hence, some form of averaging is oftendesired. Another conventional method of location estimation utilizingNMRs may include dividing the location space (e.g., a region Scontaining all possible location solutions) in some manner intosub-regions C_(i). Each sub-region C_(i), may then be associated with acharacterizing vector of measurements or a set of attributes. In thisconventional method, by averaging multiple NMRs obtained in each suchsub-region C_(b) location accuracy may be improved. U.S. Pat. No.6,496,701 to Chen provides such a technique. This technique is generallyreferred to as a disjoint partitioning of location space into regions orsub-regions C_(i). For example, Chen describes an explicit disjointpartitioning of a location region (a cell S) into sub-cells C_(i) usingthe following relationship to divide the location space into m disjointregions:S=Σ _(i=1) ^(m) C _(i)  (1)

This conventional method of dividing location space is not ideal asthere is little chance of obtaining characterizing vectors of observedmeasurements. For example, considering a user of a mobile device locatedat a window in a building, the act of the user turning around may resultin observed measurements becoming dramatically different from signalloss, etc. Further, in a challenging environment such as an urbancanyon, if a user travels five to ten feet, observed measurements maydramatically change due to blockage, multipath and/or reflections fromthe environment. Thus, the prior art is limited in determining theproper sub-cells or sub-regions C_(i) in such challenging environments.

Another conventional approach described in U.S. Patent ApplicationPublication No. 20090117907 to Wigren and in the publication entitled,“Adaptive Enhanced Cell-ID Fingerprinting Localization by Clustering ofPrecise position Measurements,” September 2007, by Wigren, groupscalibration data by similarity. The resulting groups or clusters areanalyzed to generate a most likely polygonal shape in the locationspace. Further, these groups are made in location space and aregroupings of measurements with a specified bin size for each measurementof interest. The polygons are determined as a function of theirmeasurements, and the polygons are then used to specify likely areas orregions where one assigns a location for future measurements. Such anapproach, however, is limited in determining an accurate location for atarget mobile device in challenging environments.

Therefore, there is a need in the art for a system and method to improvelocation capabilities of a communications system in such environments.In view of these needs, one embodiment of the present subject matter maydisregard the location information or location space and clusteravailable data, e.g., calibration data in observation space. Thus, inembodiments of the present subject matter, obtained NMRs (orgenerically, measurement vectors obtained during a collection processsuch as drive testing or by employing mobile devices in activecommunication with the communications network) may have one or moremeasurements coupled to location information. Embodiments of the presentsubject matter may disregard where the measurements were made and focuson grouping or clustering the measurements by similarity in theobservation space using an appropriate parameter or cluster measure.Such groupings may create observation clusters in observation space. Theobservation clusters or groups generated by embodiments of the presentsubject matter, however, are not constrained into regions in thelocation space. That is, observation clusters according to embodimentsof the present subject matter do not possess a specific association tosub-cells C_(i) such as that seen in Chen and are thus fundamentallydifferent from using a pre-specified grid (or division of the locationspace) and then assigning certain measurements to each such grid point.Further, observation clusters according to embodiments of the presentsubject matter do not possess a specific association to locationdependent polygons such as that seen in the Wigren references and arethus fundamentally different from grouping measurements by similarityand then forcing a most likely polygonal shape in the location space tocontain such measurements. Thus, if exemplary observation clustersaccording to embodiments of the present subject matter were to beexamined in the location space, the clusters would appear to formarbitrary associations of points having a connection to each otherdefined by a similarity of measurements. Further, embodiments of thepresent subject matter do not require any association of shapes orpoints in the location space to observations or measurements.

In one embodiment of the present subject matter, a candidate NMR for amobile device requiring location determination may be received. In thisembodiment, the candidate NMR may be examined against generatedobservation clusters, and then members of a subset of observationclusters along with the candidate NMR may be clustered again or“re-clustered” in the observation space to provide a location estimatefor the target mobile device. Determined locations according toembodiments of the present subject matter are thus not one of a fixedset of pre-determined assignable locations as that in Chen and Wigren;rather, determined locations may be a function of the observed clusterin which the candidate NMR finds itself, that is, a cluster havingmembers with similar observations to that of the candidate NMR.

One embodiment of the present subject matter provides a method ofdetermining the location of a mobile device in a communications network.The method may include generating a first set of NMRs for a region in acommunications network and clustering measurement information from thefirst set of NMRs as a function of a common parameter of the measurementinformation. A candidate NMR for a mobile device may be received wherebymeasurement information from the candidate NMR is compared with theclustered measurement information from the first set of NMRs. A locationof the mobile device may be determined as a function of the comparedmeasurement information.

Another embodiment of the present subject matter provides a method ofdetermining the location of a mobile device in a communications network.The method includes collecting calibration data for a region in acommunications network and providing a first set of measurement vectorsin observation space using the collected calibration data. Availablemeasurement information from the first set of vectors may be selected tocreate clusters based on a common parameter in observation space. Acandidate measurement vector for a mobile device may be received wherebymeasurement information from the candidate vector may be compared withthe measurement information from the created clusters. A location of themobile device may then be determined as a function of the comparedmeasurement information.

A further embodiment of the present subject matter provides a method ofdetermining the location of a mobile device in a communications network.The method may include providing a set of NMRs for a region in thenetwork and clustering NMRs in the first set as a function of observedmeasurement information in the NMRs. A candidate NMR for a mobile devicemay be received, and the candidate NMR associated with a selectedcluster of NMRs. The candidate NMR and a second set of NMRs may beclustered whereby the NMRs in the second set are associated with theselected cluster. A location of the mobile device may be determined as afunction of the clustered candidate NMR and second set of NMRs.

An additional embodiment of the present subject matter provides a methodfor determining the location of a mobile device in a communicationsnetwork. The method may include collecting calibration data for a regionin the network and providing a set of NMRs using the collectedcalibration data, each NMR having measurement information. NMRs in theset may be clustered without regard to the location where themeasurement information was obtained. A candidate NMR for a targetmobile device may be received, and the candidate NMR associated with aselected cluster of NMRs. Measurement information from the candidate NMRmay be combined with a second set of NMRs. A location of the mobiledevice may then be determined in the region as a function of thecombined candidate NMR and second set of NMRs.

These and other embodiments of the present subject matter will bereadily apparent to one skilled in the art to which the disclosurepertains from a perusal or the claims, the appended drawings, and thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial representation of one embodiment of the presentsubject matter.

FIG. 2 is a pictorial representation of another embodiment of thepresent subject matter.

FIG. 3 is a pictorial representation of a further embodiment of thepresent subject matter.

FIG. 4 is a pictorial representation of an additional embodiment of thepresent subject matter.

FIG. 5 is a block diagram of one embodiment of the present subjectmatter.

FIG. 6 is a block diagram of another embodiment of the present subjectmatter.

FIG. 7 is a block diagram of a further embodiment of the present subjectmatter.

FIG. 8 is a block diagram of an additional embodiment of the presentsubject matter.

DETAILED DESCRIPTION

With reference to the figures where like elements have been given likenumerical designations to facilitate an understanding of the presentsubject matter, the various embodiments of a system and method fordetermining the location of a mobile device by dynamic clustering aredescribed.

A Network Measurement Report (NMR) may be generally defined as acollection of observed measurements and/or information or data obtainedat some specific geographic location. It should be noted that the termsinformation and data are used interchangeably in this disclosure andsuch use should not limit the scope of the claims appended herewith. AnNMR may be a single vector or multiple vectors of observations orobserved measurements or may be a single vector representative ofmultiple vectors. Thus, if a mobile device collects several observationvectors and averages the same, for example, this may also be anexemplary NMR. Exemplary NMR parameters may include, but are not limitedto, an ordered list of neighboring cells or elements and/or other signalsources (the ordering may be accomplished using any observablemeasurement, e.g., power, etc.), absolute neighboring cell power levels,relative neighboring cell power differences, functions defined usingabsolute neighboring cell power levels, e.g., mean, median, k^(th)moment, cluster-mean, etc., functions defined using relative neighboringcell power differences, e.g., mean, median, k^(th) moment, cluster-mean,etc., serving cell/sector, timing advance (TA) parameter (orequivalent), round trip time (RTT) for a signal between a calibrationpoint and an external known point, Time Difference of Arrival (TDOA) ata calibration point with respect to pairs of external points locatedwithin or in proximity to a region as measured by either a receiver atthe calibration point or the external points, individual power densityfunction of each neighboring cell power level, joint power densityfunction of neighboring cell power levels, mean and variance ofneighboring cell power levels, mobile device orientation (indoors,outdoors, facing North or South, tilted upwards, azimuth, elevation,etc.), network state as reported by the network or as determined by anobserver, to name a few.

As previously noted, the NMR may include location information, which intwo dimensions may be expressed as (x_(c), y_(c)). Thus, one mayenvisage an NMR as a tall vector having two lower-most dimensions as thelocation information if in two dimensions (or if in three dimensions,the three lower-most dimensions as the location information) and otherdimensions representing the observed measurements (i.e.,“observations”). The types of exemplary parameters in an NMR noted abovemay also be separated by groups such as, but not limited to, realcontinuous numbers (e.g., time measurements, power levels, etc.),discrete numbers such as identifiers for neighboring cells (TAparameters, mobile orientation characterizations, network state, etc.),functions representing the variation of a parameter at the NMR location,and ordered lists (e.g., power level ordered list, etc.).

If the full number of dimensions are represented as n and assumingtwo-dimensional location information, observation space may generally bedefined as the space or mathematical space generated by variations ofmeasurements in the first (n−2) dimensions. Location space would then bedefined as the space generated by variations in the lower-most twodimensions. Thus, a typical NMR vector M in observation space may berepresented as:

$\begin{matrix}{M = \begin{bmatrix}P_{A} \\P_{B} \\{TA} \\{NS} \\0 \\\ldots \\P_{G}\end{bmatrix}} & (2)\end{matrix}$where P_(A), P_(B), etc. represent measured power on transmitters A, Band so forth, O represents an ordering of some subset of observedneighbor cells or transmitters, TA represents a timing advance value,and NS represents the network state.

An exemplary clustering algorithm may generally provide a means todetermine the similarity between NMRs. This similarity may be determinedin a variety of ways, for example, by employing a similarity measure ora “distance measure.” Such a similarity or distance measure may provideone with the “distance” to be applied when comparing two differentmeasurement vectors or NMR vectors such as M in Equation (2). Thus, asthe distance measure between two NMRs increases, the similaritydecreases and hence the distance provides an indication regarding thesimilarity or dissimilarity of the NMRs to each other. For example,considering a mapping of real continuous variables (e.g., power levelsand time measurements measured on neighboring cells), a distance measuremay be determined using the following relationship:d _(r) =μr∥P _(i) −P _(j)∥  (3)where P_(i), P_(j) represent vectors constructed for the power levelsobserved for multiple sites, i, j represent two different NMRs, andμ_(r) represents a constant scaling factor. More generally, given an NMRi and another NMR j, a distance measure for power may be determinedusing the relationship:d _(P) ²(i,j)=Σ_(k=1) ^(n) f(P _(i,k) ,P _(j,k))  (4)where the power components of each NMR are indexed by k and f(.)represents a function that applies to comparing power levels. A similarrelationship may also be applied to time components or other realcontinuous variables in an exemplary NMR.

In another example, considering a discrete integer variable, such as aninteger identifier (e.g., TA parameter, Network State (NS), etc.), adistance measure may be determined using the following relationship:d _(TA) ²(i,j)=g(TA_(i),TA_(j))  (5)where g(.) represents a function that applies to comparing TA values. Itfollows that in the case of network state (an identifier that capturesvariations in network settings), a similar distance measure may use thefollowing relationship:d _(NS) ²(i,j)=h(NS_(i),NS_(j))  (6)where NS_(i) represents the network state for NMR i, NS_(j) representsthe network state for NMR j, and h(.) represents a function that appliesto comparing NS values. A similar relationship may also be applied toother identifiers in an exemplary NMR. For example, if the networkoperates in one of two states where the states differ in the tilt of asingle antenna, then the state may be binary (e.g., two possible networkstates). Thus, the network state may be determined by some means ofcommunication with the network (e.g., information exchange) duringcollection of calibration data. Network state may also be necessary whena candidate NMR presents itself or is received for locationdetermination.

In another example, considering a function representing the variation ofa parameter at an NMR location (e.g., a probability distributionfunction obtained for a particular variable (received power of a TVstation as recorded in the NMR)), a distance measure may be determinedusing the following relationship:d _(f)=μ_(f) D _(f)(f _(i) ,f _(j))  (7)where D_(f)(.) represents the distance function applied to a comparisonof the two functions (one stored in each NMR), and μ_(f) represents aconstant. Further, in another embodiment, an L1 norm on space ofprobability measures or the Kullback-Leibler divergence may be usedhere.

In a further example, considering ordered lists such as a power levelordered list, etc., one embodiment may convert the ordering number to adistance measure. Generally, an ordering number may be indicative of howmany relative shifts in position occur between the observations in afirst NMR when compared to another NMR. For example, NMR i may possessan ordered label ABCDE for neighboring cell power levels (A, B, C, D, E(denoting sites)) whereas in NMR j the ordering may be BACDE, whichevaluates to an ordering number of 1 (i.e., a single shift). Manyvariations of how the ordering number is determined may be consideredbut each of them represents a measure of the distortion in order betweenthe neighboring cell power level, in this example, observed in the NMRas compared to the neighboring cell power levels observed in theobservations at the candidate point (x, y). In such an example, adistance measure may be determined using the following relationship:d _(O)(i,j)=q(O _(i) ,O _(j))  (8)where O refers to the order and q(.) represents a function that appliesto the ordered lists, converting the comparison of the order in whichcertain observations occur into an exemplary distance measure. Inanother embodiment, another appropriate distance, such as a Levenshteindistance or a Damerau-Levenshtein distance, may be employed wherebythese distances may represent a distance between two ordered lists andmay be suitable candidates for a distance measure.

In one non-limiting embodiment, considering continuous and discretemeasurements (i.e., excluding functions), an exemplary clusteringdistance measure may be determined using the following relationship:d _(L1) ²(i,j)=d _(O)(i,j)*d _(NS)(i,j)*(d _(P) ²(i,j)+d _(TA)²(i,j))  (9)where i and j each represent an NMR, d_(O)(i,j) represents a functioncomparing observed measurements for ordered lists, d_(NS)(i,j)represents a function comparing network states, d_(P) ²(i,j) representsa function comparing real continuous variables (in this case power), andd_(TA) ²(i,j) represents a function comparing discrete integer variables(in this case TA).

It should be noted that this relationship excludes any (x, y)dimensions, that is, the distance does not concern itself with locationbut only observed measurements whereby clustering is limited tooperations in observation space. More generally, Equation (9) representsa complex function or clustering algorithm assigning a distance (ascalar value) to, in this case, a pair of NMRs having multipleparameters of different types. This clustering algorithm may acceptavailable calibration data (from any or all NMRs, previously obtained orotherwise) and provide a set of observation clusters. These observationclusters represent groupings or sets of measurement information in NMRs,based on the distance measures, in observation space. It should be notedthat the terms, group, set, subset and/or cluster are usedinterchangeably throughout this disclosure, however, such use should notin any way limit the scope of the claims appended herewith. Thus,defining T_(s) as an initial grouping threshold, N_(s1) as a minimumcluster size, D_(P1) as a cluster requirement on power, D_(TA1) ascluster requirement on TA, D_(O1) as a cluster requirement on ordering,{S} as a collection of NMR vectors, {S_(O)} as an outlier subset,D_(OC1) as a distance requirement on the observation clusters, k_(m1) asthe maximum number of centers for clustering, SV(.) as a function thatextracts a serving site identifier, and C_(i) as an arbitrary NMR in thecalibration data, operation of an exemplary clustering algorithm will befurther described.

For example, an arbitrary NMR C_(i) may be selected at random from {S}.Next, all or a predetermined number of C_(j)(e.g., all C_(j)ε{S}) shouldbe extracted such that d_(L1) ²(i,j)<T_(s) and SV(C_(j))=SV(C_(i)). Thisextraction should then be assigned as {S_(i)}. If |{S_(i)}|<N_(s1), then{S_(i)} should be placed in {S_(O)} and the process repeated. If,however, |{S_(i)}|>N_(s1), then {S_(i)} is a valid set for clusteranalysis. Employing the previously defined or applicable distancemeasures, a fast algorithm (e.g., Hamerly's algorithm, etc.) may be usedfor k-means, and centers in observation space determined as appropriate.To determine the number of centers, the variable k should be incrementedstarting with k=1 until a cluster Q emerges such that for the elements(i,j) contained in Q, d_(P)(i,j)<D_(P1), d_(TA)(i,j)<D_(TA1),d_(O)(i,j)<D_(O1), and |Q|>N_(S1). Now Q may be defined as anobservation cluster. It should be noted that Q was generated without anylocation information playing a part therein. That is, Q is not dependenton (x, y) in location space. If, however, k increases to the point suchthat k>k_(m1), with no formed clusters, then C_(i) should be placed in{S_(O)} and the other elements of {S_(i)} should be placed back in {S}and the entire process repeated. Otherwise, all formed clusters Q shouldbe removed from {S}, and any residual NMRs in {S_(i)} should be placedback into {S}. If, however, |{S}|<N_(s1) then the residual should beplaced in {S_(O)}. If, |{S}|>N_(s1), then the entire process should berepeated.

Characteristic values and windows may then be assigned for eachparameter type in every observation cluster. These exemplary windowsgenerally represent a maximum and minimum allowable deviation from theobservation cluster characteristic. Further, the size of thesedeviations may be determined as a function of the measurements in theobservation cluster. For each observation cluster a pointer to thesubset of calibration data that generated the respective observationcluster may be maintained.

Upon receipt of a request for a location estimate for mobile device,e.g., a candidate NMR requiring a location estimate, it should be notedthat applicable observation clusters have been generated and any NMRsthat did not fall into the observation clusters have been rejectedand/or placed in an outlier set {S_(O)}. Additionally, for eachobservation cluster and observation cluster parameter, there may alsoexist a characteristic window. Each parameter in the candidate NMR maythen be compared against the corresponding window(s) in each observationcluster. If all parameters in the candidate NMR fit within the windowsof a corresponding observation cluster, this observation cluster may be,in one embodiment, selected for dynamic clustering. If a predeterminednumber of (e.g., at least two) observation clusters are not produced bythis exemplary process, the windows may be adjusted until at least twoobservation clusters are selected. Generally, windows may be determinedsuch that a typical NMR has a predetermined number (e.g., three or more)observation clusters with which to proceed onto additional clustering,e.g., dynamic clustering.

Once the predetermined number of observation clusters have beenidentified, the calibration data input to each of these observationclusters may be extracted into a set {S_(d)}. That is, the data that waspreviously used to create the observed cluster may now be pulled intothe set {S_(d)}, and this is repeated for each observation clusteridentified by the windowing process. The candidate NMR may now be addedto the set {S_(d)}, and an additional level of clustering commences.

Defining T_(s2) as an initial grouping threshold, N_(s2) as a minimumcluster size, D_(P2) as a cluster requirement on power, D_(TA2) ascluster requirement on TA, D_(O2) as a cluster requirement on ordering,{S′} as a collection of NMR vectors (a subset of {S}), {S_(O)} as anoutlier subset, D_(OC2) as a distance requirement on the observationclusters, k_(m2) as the maximum number of centers for clustering,operation of a further exemplary clustering algorithm will be describedand a second level clustering distance provided by:d _(L2) ²(i,j)=d _(O2)(i,j)*d _(NS2)(i,j)*(d _(P2) ²(i,j)+d _(A2)²(i,j)  (10)where i and j each represent an NMR, d_(O2)(i,j) represents a functioncomparing observed measurements for ordered lists, d_(NS2)(i,j)represents a function comparing network states, d_(P2) ²(i,j) representsa function comparing real continuous variables (in this case power), andd_(TA2) ²(i,j) represents a function comparing discrete integervariables (in this case TA). It should be noted that the suffix 2 interms in Equation (10) generally represent a “tighter” or even analtogether different distance measure used in this second levelclustering (or re-clustering) process.

Generally, this second level of clustering is similar to the firstclustering process; however, this additional level of clustering mayemploy different cluster distances and different cluster thresholds, mayoperate on a subset of the original set {S}, and may have the candidateNMR, C_(u), included. Thus, this level of clustering may now beaccomplished with the candidate NMR of unknown location and a subset ofthe original set of calibration vectors. Denoting this subset as {S′},it follows that {S′}={S_(d)}∪C_(u) whereby the operations for thesubsequent clustering process occurs in observation space.

For example, an arbitrary NMR C_(i) may be selected at random from {S′}.Next, all or a predetermined number of C_(j)(e.g., all C_(j)ε{S′})should be extracted such that d_(L2) ²(i,j)<T_(s2) andSV(C_(j))=SV(C_(i)). This extraction should then be assigned as {S_(i)}.If |{S_(i)}|<N_(s2), then {S_(i)} should be placed in {S_(O)} and theprocess repeated. If, however, |{S_(i)}|>N_(s2), then {S_(i)} is a validset for cluster analysis. Employing new and/or applicable distancemeasures, a fast algorithm may be used for k-means, and new centers inobservation space determined as appropriate. To determine the number ofcenters, the variable k should be incremented starting with k=1 until acluster Q emerges such that for the elements contained in (i, j)contained in Q, d_(P)(i,j)<D_(P2), d_(TA)(i,j)<D_(TA2),d_(O)(i,j)<D_(O2), and |Q|>N_(S2). Now Q is defined as an observationcluster. It should be noted that Q was generated without any locationinformation playing a part therein. That is, Q is not dependent on (x,y) in location space. If, however, k increases to the point such thatk>k_(m2), with no formed clusters, then C_(i) should be placed in{S_(O)} and the other elements of {S_(i)} should be placed back in {S′}and the entire process repeated. Otherwise, all formed clusters Q shouldbe removed from {S′}, and any residual NMRs in {Si} should be placedback into {S′}. If, however, |{S′}|<N_(s2) then the residual should beplaced in {S_(O)}. If, |{S′}|>N_(s2), then the entire process should berepeated. It also follows that C_(u) should not be placed in {S_(O)}.After this second clustering, one or more observation clusters may beavailable whereby the candidate NMR will be present in one of theseclusters, as well as a collection of other NMRs.

A location may now be assigned to the candidate NMR by examining the setof NMRs in the cluster having the candidate NMR. For example, a centeror centroid of the cluster having the candidate NMR may be determined inobservation space and the closest NMR to this center determined, againin observation space. The location information may then be examined forthis closest NMR to the center (now accomplished in location space) andthis location information applied to the candidate NMR. Of course, suchan example should not so limit the scope of the claims appended herewithas many other methods based on the characteristics of the observationcluster having the candidate NMR may be applied. It should be noted thatwhen an exemplary centroid is determined in the observation space, theobservations in the candidate NMR contribute to this calculation; thus,as the observations in the candidate NMR change, the centroid inobservation space also changes. This is a feature or aspect of thedynamic clustering. In another embodiment, a clustering algorithm mayemploy subset {S′} and use the candidate NMR as a cluster center increating the formed clusters Q. The location assigned to the candidateNMR may then be derived as a property of the other NMRs contained in thecluster having a center in observation space being the candidate NMR.

In the instance that multiple candidate NMRs are available for location,it may be known a-priori that these multiple NMRs all refer to nearlythe same unknown location; thus, these multiple NMRs may be used to formthe set {S′} where the closest clusters to each candidate are determinedand their formative members extracted. Subsequently, an exemplaryclustering process detailed herein may be applied. In one embodiment,when the multiple NMRs are in various clusters, a cluster containing themajority of candidate NMRs may be selected and location assignment forthe candidate NMR may proceed. Alternatively, clusters containingcandidate NMRs may each be treated as identified herein to generateindividual locations therefor and these locations can be weighted andaveraged in some manner. Such an exemplary, non-limiting weighting mayinclude a fraction of candidates in a particular cluster.

FIG. 1 is a pictorial representation of one embodiment of the presentsubject matter. With reference to FIG. 1, a typical case of signalreception in a challenging environment 100 (e.g., an urban canyon) isillustrated having two visible cell towers A, B and their respectivesignal transmissions denoted by the same label. Additional cell towersC, D, E, F and their respective signals are not shown in FIG. 1. Atcertain points in the location space P1, P2, P3, P4, P5, P6 there mayexist multiple possible observation vectors (NMRs). For example, at P1occurring NMRs may be [A, B, C, D, E, F] and [A, C, D, E, F], at P2occurring NMRs may be [A, C], at P3 occurring NMRs may be [A, B, C] and[A, B], at P4 occurring NMRs may be [A, C], at P5 occurring NMRs may be[B, A, C, D] and [B, C, D], and at P6 occurring NMRs may be [B, A, C]and [B, C]. With reference to P1, P3, P5 and P6, each of these pointsinclude valid NMRs occurring at the very same point due to the variablenature of the environment. Thus, a small movement or rotation of amobile device may alter the signal pattern it sees. It should also benoted that the distances between P2 and P3 or P3 and P4, for example,may be slight, however, the NMRs occurring at these points are differentdue to the environment. Thus, FIG. 1 provides an illustration of thevariability of the observed NMRs and associated measurements in achallenging environment.

Embodiments of the present subject matter, however, may providelocations of mobile devices in such an environment through a focus uponobservation space rather than location space, and through subsequentdivision of the observation space into observation clusters.Conventional techniques (such as those discussed in the Background) thatdivide up the location space with an expectation that each sub-cell orsub-region may be represented by a single characterizing vector ofmeasurements or attributes may average the varied observations in such asub-cell and generally result in a poor representation of the actualsituation. Such techniques, without regard to whether the division ofthe location space is accomplished before or after analysis ofcalibration data, force a particular geometric shape onto the data whichfails to adequately capture the variability of dynamic environments.

FIG. 2 is a pictorial representation of another embodiment of thepresent subject matter. With reference to FIG. 2, formation of clustersand subsequent mapping are pictorially illustrated. The environment 100in FIG. 2 is the same as depicted in FIG. 1; however, it should be notedthat, using embodiments of the present subject matter described herein,there are multiple clusters in observation space that may map to nearlythe same points in location space. For example, P2 and P4 appear toshare observation cluster {A, C}. This is noted simply forillustrational purposes, that is, embodiments of the present subjectmatter do not map observation clusters to location points duringclustering processing. Rather, mapping may be required after a candidateNMR is clustered a second time (re-clustered) or a first time with theselected set of calibration data. That is, when an appropriate locationfor a candidate NMR is determined, then the mapping of a cluster tolocation space may be performed.

FIG. 3 is a pictorial representation of a further embodiment of thepresent subject matter. With reference to FIG. 3, environmentalperturbations in observation space are illustrated such as the passageof a large object 310 (e.g., a bus or truck) which results in a changein observed signals at P1 and P2. Thus, at P1, when no large object 310is in front of the bus stop 312, an observer may have visibility tosignals A, B, C and D. Further, at P2 an observer may have visibility tosignals A, B and C. As the bus 310 moves down the street 314, anobserver at P1 may lose signal D due to blockage from the bus 310. Anobserver at P2, however, may in this instance receive signal D due to areflection of signal D off the bus 310. In this instance, the dynamicexternal environment would normally make it impossible to associate aparticular static vector of observations with either of P1 or P2.Embodiments of the present subject matter, however, may capture thevariability of signals in this environment by constructing clusters inobservation space whereby such clusters are not limited geographicallyas depicted in FIG. 2. It should be noted, however, that any significantvariation in a signal may be sufficient to generate a new measurementcluster. For example, a variation in the strength of signal D may besufficient to generate multiple observation clusters associated with P1and/or P2.

FIG. 4 is a pictorial representation of an additional embodiment of thepresent subject matter. With reference to FIG. 4, one exemplary locationdetermination process 400 is visually depicted through an illustrationof an observation space 410 having a plurality of observation clusters411-423 after an exemplary clustering process (e.g., first and/or secondlevel clustering). It should be noted that the observation space 410 maybe multi-dimensional and hence this two dimensional depiction should notso limit the scope of the claims appended herewith as the depiction ismerely an attempt at a visual representation of concepts contained inthis disclosure. Objects 430 inside each cluster 411-423 possess similarshapes to depict measurement vector similarities to each other whichpermitted the formation of the clusters 411-423. An outlier set orcluster 422 is illustrated having dissimilar objects therein. Thelocation space 440 is illustrated as a rectangular region having x, ycoordinates. Again, while a two-dimensional space is used to illustratethe concept, such a depiction should not so limit the scope of theclaims appended herewith. The location space 440 generally representsthe space of all possible (x, y) location pairs. It should be noted, forexample, that members 419 a, 419 b, 423 a, 423 b in observation clusters419, 423 may map to geographically distinct locations in location space440. This mapping is illustrated by directional arrows 442 emanatingfrom the respective observation clusters 419, 423 and terminating in thelocation space 440. Of course, any number of members in the observationclusters 411-423 may map to the location space and this example shouldnot so limit the scope of the claims appended herewith. Further, each ofthe observation clusters 411-423 include a cluster center 450 whichprovides a representative vector or point in observation space 410 thatcaptures the properties of the respective cluster 411-423. Of course, acentroid may be an exemplary but non-limiting example of such a center450,

After an exemplary clustering process according to embodiments of thepresent subject matter, one of the observation clusters 423 may containthe candidate NMR 423 c or C_(u). The cluster center 450 of the cluster423 may then be examined. It should be noted, however, that the clustercenter 450 is not necessarily coincident with any particular calibrationNMR but is generally a point in observation space 410. A location maythen be assigned to the candidate NMR 423 c by selecting an NMR 423 b inthe cluster 423 which is closest to the cluster center 450 or centroidin observation space 410. Viewing the location space 440 and using thecorresponding location space information 445 for the selected NMR 423 b,an estimated location 445 may be assigned to the candidate NMR 423 c orC_(u). Of course, other methods of assigning a location may be basedupon various operations applied to the members of the cluster 423 and/orby any of the related methods discussed in this disclosure.

FIG. 5 is a block diagram of one embodiment of the present subjectmatter. With reference to FIG. 5, a method 500 for determining thelocation of a mobile device in a communications network is provided. Atstep 510, a first set of NMRs may be generated for a region in thecommunications network. Exemplary NMRs may be, but are not limited to, acollection of measurement parameters observed at a geographic locationin the communications network. Such measurement parameters may include,for example, power levels, power differences, functions defined by powerlevels, functions defined by power differences, serving cell, servingsector, Timing Advance, Timing Advance equivalent, an ordered list ofsignal sources, round trip time, time difference of arrival, powerdensity function of power levels, joint power density function of powerlevels, mobile device orientation, network state reported by thenetwork, network state determined by an observing device, andcombinations thereof. Further, the NMR may represent a single vector ofobserved measurement information, multiple vectors of observedmeasurement information, or a single vector representing multiplevectors of observed measurement information. In one embodiment, themethod 500 may further include collecting calibration data from drivetesting to thereby obtain an NMR and/or may include collectingcalibration data from mobile devices in active communication in thecommunications network to thereby obtain an NMR.

Measurement information from the first set of NMRs may be clustered atstep 520 as a function of a common parameter of the measurementinformation. The common parameter generally may be a measurerepresenting a commonality between measurement information of NMRs inthe first set. In one embodiment, the common parameter may be determinedas a function of the following relationship: d_(L1)²(i,j)=d_(O)(i,j)*d_(NS)(i,j)*(d_(RCV) ²(i,j)+d_(DIV) ²(i,j)) where iand j each represent an NMR, d_(O)(i,j) represents a function comparingthe observed measurements for ordered lists, d_(NS)(i,j) represents afunction comparing network states, d_(RCV) ²(i,j) represents a functioncomparing real continuous variables, and d_(DIV) ²(i,j) represents afunction comparing discrete integer variables. In one embodiment, step520 may include taking available measurement information from the firstset of NMRs and providing a set of measurement information clustersbased on common parameters in observation space. In a furtherembodiment, step 520 may include selecting an arbitrary NMR from thefirst set of NMRs and extracting NMRs from the first set having a commonparameter with the arbitrary NMR. A subset of NMRs may be generatedwhich includes the extracted NMRs and the arbitrary NMR. In thisembodiment, if the subset of NMRs is less than a predeterminedthreshold, then the aforementioned steps may be iterated until thethreshold is met. If, however, the subset of NMRs meets thepredetermined threshold, then a focus of the subset of NMRs may bedetermined in observation space.

A candidate NMR for a mobile device may be received at step 530, and atstep 540 measurement information from the candidate NMR compared withthe clustered measurement information from the first set of NMRs. In oneembodiment, step 540 may include assigning windows for each parametertype in the clustered measurement information and comparing measurementinformation from the candidate NMR with the clustered measurementinformation from the first set of NMRs using assigned windows of thecorresponding parameter type. In this embodiment, if the comparedmeasurement information from the candidate NMR does not substantiallycorrespond with a respective window, then the respective window may beadjusted until the compared measurement information from the candidateNMR substantially corresponds. This measurement information may then bere-clustered to form a second set of NMRs. In this embodiment, if thecompared measurement information from the candidate NMR substantiallycorresponds with a respective window, however, then a location of themobile device may be determined as a function of the comparedmeasurement information. One exemplary method or process ofre-clustering may include extracting measurement information from thesecond set of NMRs (the second set comprising at least the candidate NMRand NMRs from the first set) and selecting an arbitrary NMR from thesecond set of NMRs. In this re-clustering NMRs from the second sethaving a common parameter with the arbitrary NMR may be extracted, and asubset of NMRs generated which includes the extracted NMRs and thearbitrary NMR. In this embodiment, if the subset of NMRs is less than asecond threshold, then the previous steps should be iterated until thesecond threshold is met; however, if the subset of NMRs meets the secondthreshold, then a focus of the subset of NMRs in observation space maybe determined.

At step 550, a location of the mobile device may then be determined as afunction of the compared measurement information. In one embodiment, thedetermined location may be a location corresponding to a centroid of theclustered measurement information or may be a location corresponding tothe closest NMR to a centroid of the clustered measurement information.In another embodiment, the method 500 may include the step ofre-clustering the compared measurement information using a second set ofNMRs, the second set comprising at least the candidate NMR and NMRs fromthe first set.

FIG. 6 is a block diagram of another embodiment of the present subjectmatter. With reference to FIG. 6, a method 600 is provided fordetermining the location of a mobile device in a communications network.At step 610, calibration data may be collected for a region in acommunications network, and a first set of measurement vectors inobservation space provided using the collected calibration data at step620. At step 630, available measurement information from the first setof vectors may be selected to create clusters based on a commonparameter in observation space. In one embodiment, step 630 may includeselecting a random vector from the set of vectors and extracting vectorsfrom the set having a common parameter with the random vector. In thisembodiment, a cluster of vectors may be generated which includes theextracted vectors and the arbitrary vector. An exemplary commonparameter may be, but is not limited to, a measure representing acommonality between measurement information of vectors in the set.Another exemplary common parameter may be determined as a function ofthe following relationship: d_(L1)²(i,j)=d_(O)(i,j)*d_(NS)(i,j)*(d_(RCV) ²(i,j)+d_(DIV) ²(i,j)) where iand j each represent an NMR, d_(O)(i,j) represents a function comparingthe observed measurements for ordered lists, d_(NS)(i,j) represents afunction comparing network states, d_(RCV) ²(i,j) represents a functioncomparing real continuous variables, and d_(DIV) ²(i,j) represents afunction comparing discrete integer variables. Upon receipt of acandidate measurement vector for a mobile device at step 640,measurement information from the candidate vector may be compared withthe measurement information from the created clusters at step 650. Inone embodiment, step 650 may include associating the candidate vectorwith a selected cluster of vectors and clustering the candidate vectorand a second set of vectors whereby the vectors in the second set areassociated with the selected cluster. At step 660, a location of themobile device may be determined as a function of the comparedmeasurement information.

FIG. 7 is a block diagram of a further embodiment of the present subjectmatter. With reference to FIG. 7, a method 700 for determining thelocation of a mobile device in a communications network is provided. Atstep 710, a set of NMRs for a region in the network may be provided.NMRs in this first set may then be clustered at step 720 as a functionof observed measurement information in the NMRs. In one embodiment, step720 may include selecting a random NMR from the first set of NMRs andextracting NMRs from the first set having a common parameter with therandom NMR. In this embodiment, a cluster of NMRs may be generated whichincludes the extracted NMRs and the arbitrary NMR. An exemplary butnon-limiting common parameter may be determined as a function of thefollowing relationship: d_(L1) ²(i,j)=d_(O)(i,j)*d_(NS)(i,j)*(d_(RCV)²(i,j)+d_(DIV) ²(i,j)) where i and j each represent an NMR, d_(O)(i,j)represents a function comparing the observed measurements for orderedlists, d_(NS)(i,j) represents a function comparing network states,d_(RCV) ²(i,j) represents a function comparing real continuousvariables, and d_(DIV) ²(i,j) represents a function comparing discreteinteger variables. Upon receipt of a candidate NMR for a mobile deviceat step 730, the candidate NMR may be associated with a selected clusterof NMRs at step 740. The candidate NMR and a second set of NMRs may thenbe clustered at step 750, and a location of the mobile device determinedat step 760 as a function of the clustered candidate NMR and second setof NMRs whereby the NMRs in the second set are associated with theselected cluster. In one embodiment, the determined location may be afunction of a centroid of the clustered candidate NMR and second set ofNMRs or may be the closest NMR to a centroid of the clustered candidateNMR and second set of NMRs.

It should be noted that the proximity described herein is measured inobservation space rather than in location space. That is, the candidateNMR(s) do not include location information but include observationinformation. Thus, exemplary clustering operations are performed inobservation space, and proximity noted in observation space. Forexample, if a centroid in observation space has been determined, oneoption would be to select the closest calibration NMR to the centroid(most proximate in observation space), and then assign locationinformation for this calibration data NMR as the estimated location.This may generally be defined as a dynamic aspect of the claimed subjectmatter as the clusters do not remain static, but are rather influencedby the specific observation information contained in the candidateNMR(s). Solely for clarification purposes, a static scheme may berepresented in an instance having some pre-calculated clusters inobservation space. When a candidate NMR needs to be located, one wouldselect the closest cluster in observation space and simply use afunction of the location information available for the cluster membersto assign a location. This assigned location may thus be a function onlyof the pre-calculated clusters. In a dynamic scheme, however, proximateclusters are determined and may be re-clustered with candidate NMRs withsubsequent location assignment. This assigned location may thus bedependent upon which NMRs are in the closest clusters and observationinformation in the candidate NMR(s). In the dynamic scheme, it followsthat even if matching clusters may remain the same, an assigned locationmay change depending on the specific observation information in thecandidate NMR(s),

FIG. 8 is a block diagram of an additional embodiment of the presentsubject matter. With reference to FIG. 8, a method 800 for determiningthe location of a mobile device in a communications network is provided.The method 800 may include at step 810 collecting calibration data for aregion in the network and providing a set of NMRs using the collectedcalibration data at step 820, each NMR having measurement information.At step 830, NMRs in the set may be clustered without regard to thelocation where the measurement information was obtained. Upon receipt ofa candidate NMR for a target mobile device at step 840, the candidateNMR may be associated with a selected cluster of NMRs at step 850 andmeasurement information from the candidate NMR combined with a secondset of NMRs at step 860. A location of the mobile device in the regionmay then be determined at step 870 as a function of the combinedcandidate NMR and second set of NMRs. In one embodiment, the determinedlocation may be a centroid of the combined measurement information ormay be the closest NMR to a centroid of the combined measurementinformation.

The present disclosure may be implemented by a general purpose computerprogrammed in accordance with the principals discussed herein. It may beemphasized that the above-described embodiments, particularly any“preferred” embodiments, are merely possible examples ofimplementations, merely set forth for a clear understanding of theprinciples of the disclosure. Many variations and modifications may bemade to the above-described embodiments of the disclosure withoutdeparting substantially from the spirit and principles of thedisclosure. All such modifications and variations are intended to beincluded herein within the scope of this disclosure and the presentdisclosure and protected by the following claims.

Embodiments of the subject matter and the functional operationsdescribed in this specification can be implemented in digital electroniccircuitry, or in computer software, firmware, or hardware, including thestructures disclosed in this specification and their structuralequivalents, or in combinations of one or more of them. Embodiments ofthe subject matter described in this specification can be implemented asone or more computer program products, i.e., one or more modules ofcomputer program instructions encoded on a tangible program carrier forexecution by, or to control the operation of, data processing apparatus.The tangible program carrier can be a computer readable medium. Thecomputer readable medium can be a machine-readable storage device, amachine-readable storage substrate, a memory device, or a combination ofone or more of them.

The term “processor” encompasses all apparatus, devices, and machinesfor processing data, including by way of example a programmableprocessor, a computer, or multiple processors or computers. Theprocessor can include, in addition to hardware, code that creates anexecution environment for the computer program in question, e.g., codethat constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, or a combination of one or moreof them.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, or declarative orprocedural languages, and it can be deployed in any form, including as astandalone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment. A computer program does notnecessarily correspond to a file in a file system. A program can bestored in a portion of a file that holds other programs or data (e.g.,one or more scripts stored in a markup language document), in a singlefile dedicated to the program in question, or in multiple coordinatedfiles (e.g., files that store one or more modules, sub programs, orportions of code). A computer program can be deployed to be executed onone computer or on multiple computers that are located at one site ordistributed across multiple sites and interconnected by a communicationnetwork.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., a field programmable gate array (FPGA) or anapplication specific integrated circuit (ASIC).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for performing instructions and one or more data memorydevices for storing instructions and data. Generally, a computer willalso include, or be operatively coupled to receive data from or transferdata to, or both, one or more mass storage devices for storing data,e.g., magnetic, magneto optical disks, or optical disks. However, acomputer need not have such devices. Moreover, a computer can beembedded in another device, e.g., a mobile telephone, a personal digitalassistant (PDA), a mobile audio or video player, a game console, aGlobal Positioning System (GPS) receiver, to name just a few.

Computer readable media suitable for storing computer programinstructions and data include all forms data memory includingnon-volatile memory, media and memory devices, including by way ofexample semiconductor memory devices, e.g., EPROM, EEPROM, and flashmemory devices; magnetic disks, e.g., internal hard disks or removabledisks; magneto optical disks; and CD ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,special purpose logic circuitry.

To provide for interaction with a user, embodiments of the subjectmatter described in this specification can be implemented on a computerhaving a display device, e.g., a cathode ray tube (CRT) or liquidcrystal display (LCD) monitor, for displaying information to the userand a keyboard and a pointing device, e.g., a mouse or a trackball, bywhich the user can provide input to the computer. Other kinds of devicescan be used to provide for interaction with a user as well; for example,input from the user can be received in any form, including acoustic,speech, or tactile input.

Embodiments of the subject matter described in this specification can beimplemented in a computing system that includes a back end component,e.g., as a data server, or that includes a middleware component, e.g.,an application server, or that includes a front end component, e.g., aclient computer having a graphical user interface or a Web browserthrough which a user can interact with an implementation of the subjectmatter described is this specification, or any combination of one ormore such back end, middleware, or front end components. The componentsof the system can be interconnected by any form or medium of digitaldata communication, e.g., a communication network. Examples ofcommunication networks include a local area network (LAN) and a widearea network (WAN), e.g., the Internet.

The computing system can include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the claimed subject matter, butrather as descriptions of features that may be specific to particularembodiments. Certain features that are described in this specificationin the context of separate embodiments can also be implemented incombination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

As shown by the various configurations and embodiments illustrated inFIGS. 1-8, a method and system for determining the location of a mobiledevice by dynamic clustering have been described.

While preferred embodiments of the present subject matter have beendescribed, it is to be understood that the embodiments described areillustrative only and that the scope of the invention is to be definedsolely by the appended claims when accorded a full range of equivalence,many variations and modifications naturally occurring to those of skillin the art from a perusal hereof.

What we claimed is:
 1. A method of determining the geolocation of amobile device operating in a region served by a communications network,the method comprising the steps of: (a) determining, in observationspace, an observation cluster of measurement data from a first set ofnetwork measurement reports (“NMRs”) from the communication network; (b)comparing measurement data from a candidate NMR for a mobile device withthe determined observation cluster of measurement data; and (c)determining a location of the mobile device as a function of thecompared measurement information, wherein the NMR represents a singlevector of observed measurement information, multiple vectors of observedmeasurement information, or a single vector representing multiplevectors of observed measurement information.
 2. The method of claim 1wherein the location is determined as a function of a locationcorresponding to the compared measurement information.
 3. The method ofclaim 1 wherein the location is determined by: (a) determining acentroid in the observation space based on the measurement data from theset of NMRs from the communication network and based on the measurementdata from the NMR for the mobile device; (b) calculating, based on thedetermined centroid, a weight for each of select ones of the NMRs fromthe communication network and from the NMR for the mobile device; (c)applying the calculated weight to a location for each of said selectones of the NMRs from the communication network; and (d) calculating aweighted sum of the locations.
 4. The method of claim 1 wherein ones ofthe NMRs in the first set of NMRs are measured at different geographiclocations in the communications network.
 5. The method of claim 1wherein the measurement data includes data selected from the groupconsisting of power levels, power differences, functions defined bypower levels, functions defined by power differences, serving cell,serving sector, Timing Advance, Timing Advance equivalent, an orderedlist of signal sources, round trip time, time difference of arrival,power density function of power levels, joint power density function ofpower levels, mobile device orientation, network state reported by thenetwork, network state determined by an observing device, andcombinations thereof.
 6. The method of claim 1 wherein the observationcluster is determined as a function of a common parameter of themeasurement data in the observation space.
 7. The method of claim 1wherein the common parameter is determined as a function of thefollowing relationship:d _(L1) ²(i,j)=d _(O)(i,j)*d _(NS)(i,j)*(d _(RCV) ²(i,j)+d _(DIV)²(i,j)) where i and j each represent an NMR, d_(O)(i,j) represents afunction comparing the observed measurements for ordered lists,d_(NS)(i,j) represents a function comparing network states, d_(RCV)²(i,j) represents a function comparing real continuous variables, andd_(DIV) ²(i,j) represents a function comparing discrete integervariables.
 8. The method of claim 1 further comprising the step ofdetermining a second observation cluster using a second set of NMRs,wherein the second set of NMRs includes at least the candidate NMR andNMRs from the first set.
 9. A method of determining the geolocation of amobile device operating in a region served by a communications network,the method comprising the steps of: (a) determining, in observationspace, an observation cluster of measurement data from a first set ofnetwork measurement reports (“NMRs”) from the communication network; (b)comparing measurement data from a candidate NMR for a mobile device withthe determined observation cluster of measurement data; and (c)determining a location of the mobile device as a function of thecompared measurement information, wherein the step of determining anobservation cluster further comprises the steps of: (i) selecting anarbitrary NMR from the first set of NMRs; (ii) extracting NMRs from thefirst set of NMRs having a common parameter with the arbitrary NMR;(iii) generating a subset of NMRs including the extracted NMRs and thearbitrary NMR; (iv) if the subset of NMRs contains fewer NMRs than apredetermined threshold, then iterating steps (i)-(iii) until thethreshold is met; and (v) if the subset of NMRs meets the predeterminedthreshold, then determining a focus of the subset of NMRs in theobservation space.
 10. The method of claim 9 wherein the step ofcomparing measurement data further comprises: (i) assigning windows foreach parameter type in the clustered measurement information; (ii)comparing measurement information from the candidate NMR with theclustered measurement information from the subset of NMRs using assignedwindows of a corresponding parameter type; (iii) if the comparedmeasurement information from the candidate NMR does not substantiallycorrespond with a respective window, then adjusting the respectivewindow until the compared measurement information from the candidate NMRsubstantially corresponds and re-clustering measurement information froma second set of NMRs; and (iv) if the compared measurement informationfrom the candidate NMR substantially corresponds with a respectivewindow, then determining a location of the mobile device as a functionof the location corresponding to the compared measurement information.11. The method of claim 10 wherein the re-clustering further comprises:(i) extracting measurement information from the second set of NMRs, thesecond set comprising at least the candidate NMR and NMRs from thesubset or first set; (ii) selecting an arbitrary NMR from the second setof NMRs; (iii) extracting NMRs from the second set having a commonparameter with the arbitrary NMR; (iv) generating another subset of NMRsincluding the extracted NMRs and the arbitrary NMR; (v) if the anothersubset of NMRs contains fewer NMRs than a second threshold, theniterating steps (ii)-(iv) until the second threshold is met; and (vi) ifthe subset of NMRs meets the second threshold, then determining a focusof the subset of NMRs in the observation space.
 12. A method ofdetermining the geolocation of a mobile device operating in a regionserved by a communications network, the method comprising the steps of:(a) determining, in observation space, an observation cluster ofmeasurement data from a first set of network measurement reports(“NMRs”) from the communication network; (b) comparing measurement datafrom a candidate NMR for a mobile device with the determined observationcluster of measurement data; and (c) determining a location of themobile device as a function of the compared measurement information,wherein the step of comparing measurement data further comprises: (i)assigning windows for each parameter type in the clustered measurementinformation; (ii) comparing measurement information from the candidateNMR with the clustered measurement information from the first set ofNMRs using assigned windows of a corresponding parameter type; (iii) ifthe compared measurement information from the candidate NMR does notsubstantially correspond with a respective window, then adjusting therespective window until the compared measurement information from thecandidate NMR substantially corresponds and re-clustering measurementinformation from a second set of NMRs; and (iv) if the comparedmeasurement information from the candidate NMR substantially correspondswith a respective window, then determining a location of the mobiledevice as a function of the location corresponding to the comparedmeasurement information.
 13. The method of claim 12 wherein there-clustering further comprises: (i) extracting measurement informationfrom the second set of NMRs, the second set comprising at least thecandidate NMR and NMRs from the first set; (ii) selecting an arbitraryNMR from the second set of NMRs; (iii) extracting NMRs from the secondset having a common parameter with the arbitrary NMR; (iv) generating asubset of NMRs including the extracted NMRs and the arbitrary NMR; (v)if the subset of NMRs is less than a second threshold, then iteratingsteps (ii)-(iv) until the second threshold is met; and (vi) if thesubset of NMRs meets the second threshold, then determining a focus ofthe subset of NMRs in the observation space.